Mesa (master): i965/fs: Don' t set exec_all on instructions wider than the original in lower_simd_width.
Francisco Jerez
currojerez at kemper.freedesktop.org
Wed Jul 29 16:29:06 UTC 2015
Module: Mesa
Branch: master
Commit: 4529916dfd227af6c4e151f45261db22157fe45f
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=4529916dfd227af6c4e151f45261db22157fe45f
Author: Francisco Jerez <currojerez at riseup.net>
Date: Mon Jul 27 18:42:31 2015 +0300
i965/fs: Don't set exec_all on instructions wider than the original in lower_simd_width.
This could have led to somewhat increased bandwidth usage for lowered
texturing instructions on Gen4 (which is the only case in which
lower_width may be greater than inst->exec_size). After the previous
patches the invariant mentioned in the comment should no longer be
assumed by any of the other optimization and lowering passes, so the
exec_all() call shouldn't be necessary anymore.
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 57e4dd7..4947f24 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -4163,10 +4163,15 @@ fs_visitor::lower_simd_width()
const unsigned lower_width = get_lowered_simd_width(devinfo, inst);
if (lower_width != inst->exec_size) {
- /* Builder matching the original instruction. */
+ /* Builder matching the original instruction. We may also need to
+ * emit an instruction of width larger than the original, set the
+ * execution size of the builder to the highest of both for now so
+ * we're sure that both cases can be handled.
+ */
const fs_builder ibld = bld.at(block, inst)
.exec_all(inst->force_writemask_all)
- .group(inst->exec_size, inst->force_sechalf);
+ .group(MAX2(inst->exec_size, lower_width),
+ inst->force_sechalf);
/* Split the copies in chunks of the execution width of either the
* original or the lowered instruction, whichever is lower.
@@ -4189,14 +4194,11 @@ fs_visitor::lower_simd_width()
split_inst.exec_size = lower_width;
split_inst.eot = inst->eot && i == n - 1;
- /* Set exec_all if the lowered width is higher than the original
- * to avoid breaking the compiler invariant that no control
- * flow-masked instruction is wider than the shader's
- * dispatch_width. Then transform the sources and destination and
- * emit the lowered instruction.
+ /* Select the correct channel enables for the i-th group, then
+ * transform the sources and destination and emit the lowered
+ * instruction.
*/
- const fs_builder lbld = ibld.exec_all(lower_width > inst->exec_size)
- .group(lower_width, i);
+ const fs_builder lbld = ibld.group(lower_width, i);
for (unsigned j = 0; j < inst->sources; j++) {
if (inst->src[j].file != BAD_FILE &&
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